Archives of Gynecology and Obstetrics (2019) 299:733–740 https://doi.org/10.1007/s00404-019-05066-3 MATERNAL-FETAL MEDICINE The increasing role of a retained placenta in postpartum blood loss: a cohort study Hellen McKinnon Edwards1 · Jens Anton Svare1 · Anne Juul Wikkelsø2 · Jeannet Lauenborg1 · Jens Langhof‑Roos3 Received: 21 February 2018 / Accepted: 25 January 2019 / Published online: 7 February 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Purpose To describe the association between quantity of blood loss, duration of the third stage of labour, retained placenta and other risk factors, and to describe the role of a retained placenta depending on the cutof used to defne postpartum haemorrhage. Methods Cohort study of all vaginal deliveries at two Danish maternity units between 1 January 2009 and 31 December 2013 (n = 43,357), univariate and multivariate linear regression statistical analyses. Results A retained placenta was shown to be a strong predictor of quantity of blood loss and duration of the third stage of labour a weak predictor of quantity of blood loss. The predictive power of the third stage of labour was further reduced in the multivariate analysis when including retained placenta in the model. There was an increase in the role of a retained placenta depending on the cutof used to defne postpartum haemorrhage, increasing from 12% in cases of blood loss ≥ 500 ml to 53% in cases of blood loss ≥ 2000 ml Conclusion The predictive power of duration of the third stage of labour in regard to postpartum blood loss was diminished by the infuence of a retained placenta. A retained placenta was, furthermore, present in the majority of most severe cases. Keywords Postpartum haemorrhage · Retained placenta · Third stage of labour · Pregnancy blood loss Introduction also in more severe cases [5, 6]. The major cause of PPH has typically been attributed to lack of tone in the uterus, i.e., It is well-known worldwide that the leading direct cause of atony, with the remainder of causes associated with either maternal morbidity and mortality in both developing and trauma to the birth canal, retained tissue, or coagulopathy developed regions is postpartum haemorrhage (PPH) [1]. [7]. However, the cutof used to defne PPH and the distri- In recent years, the awareness towards PPH has increased bution of causes varies between studies, leaving us unsure further due to a rising incidence in developed regions [2–4]. whether it is the diferent cohorts or the diferent defnitions This rise has not only been seen in cases of mild PPH, but that cause the variation in distribution [5, 8–10]. Prolonged duration of the third stage of labour has been identifed as one of the risk factors for PPH, leading to most Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s0040 4-019-05066 -3) contains national guidelines recommending active management of supplementary material, which is available to authorized users. the third stage of labour and manual removal of the placenta if this exceeds 30 min or if there is bleeding [5, 11–13]. * Hellen McKinnon Edwards Recent studies have, however, reported that the increased [email protected] risk of PPH already exists if the third stage of labour 1 Department of Obstetrics and Gynaecology, Copenhagen exceeds 15–20 min, suggesting that manual removal of the University Hospital Herlev, Herlev Ringvej 75, 2730 Herlev, placenta should be performed early on regardless of blood Denmark loos [14–16]. Up to 90% of placentas are delivered within 2 Department of Anaesthesia and Intensive Care Medicine, 10 min [15, 17], with the majority of remaining cases hav- Copenhagen University Hospital Herlev, Herlev Ringvej 75, ing a prolonged duration of the third stage of labour due to a 2730 Herlev, Denmark placenta that is trapped, adherent, or even abnormal invasive 3 Department of Obstetrics, Juliane Marie Centre, (AIP) [18, 19]. These disorders are all risk factors for PPH Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark Vol.:(0123456789)1 3 734 Archives of Gynecology and Obstetrics (2019) 299:733–740 and often require manual removal of the placenta irrespec- to the registry for less than 1 year of the study period, we tive of the length of the third stage of labour. However, the excluded these hospitals (3 centres/4591 deliveries). majority are difcult to diagnose before manual removal has taken place [19], with the exception of trapped placenta Variables that sometimes can be diagnosed by postpartum ultrasound. The question is, therefore, whether some placentas removed The following variables from the database were included manually could have been delivered spontaneously without in this study: maternal age, parity, previous caesarean sec- an increased risk of PPH regardless of the length of the third tion, singleton or multiple pregnancy, hypertensive dis- stage of labour. orders of the mother, antepartum haemorrhage, placenta In the present study, we analysed data from a large praevia, abnormal invasive placenta, presentation of the regional birth cohort to investigate the association between foetus, amniotic fuid abnormalities, preterm premature the duration of the third stage of labour, a retained placenta, rupture of membranes (PPROM), premature rupture of other risk factors, and quantity of postpartum blood loss. membranes (PROM), date and time of delivery, hospital, Furthermore, we investigate whether the proportion of cases gestational age at delivery, induction of labour, augmenta- with retained placenta depended on the cutof used to defne tion of labour, fever during labour, mode of delivery, epi- PPH. siotomy, genital tract lacerations, epidural analgesia, uter- ine rupture, placental abruption, shoulder dystocia, uterine inversion, quantity of postpartum blood loss (ml), duration of labour (min), duration of expulsive eforts (min), time Methods of delivery or removal of the placenta, retained placenta, and manual removal of tissue or placenta. The diagnosis Study population “retained placenta” is used in the registry when it is removed manually, regardless of the length of the third stage of This retrospective cohort study is based on data from the labour. Abnormal invasive placenta, retained placenta, and Copenhagen Obstetric Database, where all births in the manual removal of placental tissue were grouped together Capital Region of Copenhagen are registered. Data from as “retained placenta” for our study. Cases with missing or 01 January 2009 until 31 December 2013 were retrieved. invalid durations of labour, expulsive eforts, and third stage We acquired permission from the Danish Data Protection of labour were excluded from the linear regression model. Agency (ID HEH-2014-078). No permission was required We were not able to retrieve sufcient data on the previ- from the Danish Ethics Committee according to Danish ous PPH, BMI, and birthweight. Uterine atony is not coded legislation. in our database. Outcome of quantity of postpartum blood The Obstetric Database includes data on maternal demo- loss was not only analysed as a continuous variable, but graphics, parity, labour, and delivery, and holds a high also using four diferent defnitions of PPH with cutofs of: internal validity with kappa coefcients from 0.7–1.0 [20]. ≥ 500 ml, ≥ 1000 ml, ≥ 1500 ml, and ≥ 2000 ml. Duration Midwives register baseline data and interventions both dur- of the third stage of labour was calculated from the time of ing and after labour, while obstetricians or senior midwives delivery of the neonate until the time of delivery of placenta supply specialist diagnosis after the patients have been dis- —either spontaneously or by manual removal. charged from hospital [20]. Estimations of blood loss at the hospitals are based primarily on weighing of pads, collector Statistical analysis bags, and collection during peripartum surgery. Combined weighing of standard pads and the content of collector bags All data analyses were carried out using SPSS 22.0 (SPSS, are used as a standard to determine blood loss on all labour Chicago, IL, USA). Quantity of postpartum blood loss and beds at the included hospitals. The Danish national guideline durations are presented as medians and interquartile ranges recommends routine administration of 10 IU of oxytocin at (IQR) due to their non-parametric distribution. Quantity of delivery, and manual removal of the placenta within 30 min postpartum blood loss was logarithmic transformed (log10) or immediately if there is active bleeding [11]. Inclusion due to substantially skewed distribution. Risk factors for criteria were all vaginal births (singleton and multiple preg- quantity of postpartum blood loss were analysed using nancies) from 22 to 43 weeks of gestation, as the majority univariate and multivariate linear regression analyses pre- of cases with GA >43 + 6 were interpreted as faulty registra- sented as β-coefcients and 95% confdence intervals (CI). tion. All cases with missing data on blood loss (897 deliver- Due to the logarithmic transformation of quantity of post- ies), or postpartum blood loss lower than 50 ml (68 deliver- partum blood loss, β values need to be back-transformed by ies) were excluded, due to the assumption that all women raising 10 to the power of each value and subtracting one bleed at least 50 ml. Due to some hospitals only reporting (10x-1); and can then be interpreted as percent change in 1 3 Archives of Gynecology and Obstetrics (2019) 299:733–740 735 the predicted quantity of postpartum blood loss. Thereby, The National Danish Birth the predicted mean blood loss can be calculated for each Registry 01 January 2009 to risk factor using the constant β and the percent change. The 31 December 2013 predicted mean blood loss for a combination of risk factors 64,464 deliveries can be calculated by adding the β coefcient for each risk Excluded due to the centres reporting to the Obstetric Database for less than factor to the β coefcient of the constant, before “back-trans- one year (3 centres) forming”.